The main purpose of traditional hathayoga is to preserve the essence of life, called bindu. It was thought that bindu dripped down from a place in the head and was burned up by the digestive fire in the abdomen. As we get older, our supply of bindu runs out and we age. By preserving bindu we can therefore lengthen our lives. The concept of bindu has faded in the modern era as the focus on physical fitness and western anatomy has grown.

There are two methods to conserve this essence: 1) tipping the body upside down, a technique called viparitakarani (inversion), and 2) drawing bindu upward by placing the breath into the "central channel." These two methods inform many of the practices that we do in yoga.

VIPARITAKARANI MUDRAViparitakarani is often translated as "inverted action," "the reverser" or simply "inversion." The only real instruction we get from old texts is to place the head below the abdomen. This means that Headstand, Shoulderstand and the mudra called viparitakarani qualify. Its goal is to halt the effect of gravity which pulls bindu downward.

THE CENTRAL CHANNELTechniques for drawing bindu upward in the central channel of the body are called mudras. There are 10 or 11 mudras in traditional hathayoga, some of which have been converted into asanas and some of which have been forgotten. They are usually done seated, with pressure from one or both heels on the perineum, and some sort of breath control. This is thought to prevent bindu from falling down and even draw it upward.

As the centuries progressed, the concept of bindu was largely replaced by the concept of kundalini, a powerful energy that lies dormant at the base of the spine. The same techniques are used to "awaken" this energy and draw it upward, much like they did for bindu​.